Sulfonation of diamides of meta-phenylenediamine

ABSTRACT

Process for sulfonating a diamide of a meta-phenylenediamine, for example, a film forming polyamide of meta-phenylenediamine and isophthaloyl chloride, with a sulfonating agent, for example, sulfur trioxide, which process comprises contacting the diamide and sulfonating agent in the presence of an N,N-dialkylacylamide, for example, N,N-dimethylformamide, until the desired sulfonation is completed.

0 United States Patent 1191 1111 3,839,294 Manos Oct. 1, 1974 [54] SULFONATION 0F DIAMIDES OF 3,654,237 4/1972 K0581 et al. 260 78 META PHENYLENEDIAMINE 3,663,509 5/1972 Bonnard et a]. 260/49 3,665,054 5/1972 Burrows et aL... 260/857 Inventorl Phlllp Manos, wllmlngton, 3,719,641 3/1973 Campbell et al 260/78 [73] Assignee: E. I. du Pont de Nemours and Company, Wilmingt D L Primary ExaminerLester L. Lee

Art A F b Filed: y 1,1972 orney gent 0r zrm Lou1s H Rom ach Process for sulfonating a diamide of a meta- [52] U.S. Cl. 260/78 SC, 260/558 S phenylenediamine, for example, a film forming poly [51] ll lt. Cl C08g 20/38 amide of meta phenylenediamine and isophthaloyl [58] Fleld of Search 260/78 SC, 558 S chloride, with a nagent for example, Sulfur trioxide, which process comprises contacting the di- [56] References C'ted amide and sulfonating agent in the presence ofan UNITED STATES P NT N,N-dialkylacylamide, for example, N,N-dimethylfor- 3,438,949 4 1969 Crovatt,1r 260/78 mamide, until the desired lf n is mple e 3,542,743 11/1970 Flamand 3,576,590 4/1971 Hirsch 8/1155 8 Chums N0 Drawmgs SULFONATION OF DIAMIDES OF META-PHENYLENEDIAMINE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to the sulfonation of diamides of meta-phenylenediamine.

2. Description of the Prior Art Polyamides containing 2,4-diaminobenzenesulfonic acid units are useful in the textile fiber and selective permeation separation arts. U.S. Pat. No. 3,184,436 discloses copolymers which have increased affinity for basic dyes and which are prepared by condensing mixtures of meta-phenylenediamine and 2,4-diaminobenz'enesulfonic acid with isophthaloyl chloride in hexamethylphosphoramide and in dimethylacetamide. U.S. Pat. No. 3,576,632 discloses the usefulness of hollow fiber permselective barrier membranes of such polymers which are prepared in a similar manner. The preparation of these polymers of high molecular weight and high sulfonic acid content by direct sulfonation of the polyamide is difficult, particularly since the rate of polymer degradation may exceed the rate of sulfonation. Moreover, such sulfonations generally must be carried out on polyamides which have been isolated from their preparation reaction mixtures.

Gilbert in Sulfonation and Related Reactions, In-

terscience, New York, (1965), Kittila in Dimethylformamide Chemical Uses, pages 213-216Du Pont (1967) and U.S. Pat. No. 2,506,580 disclose that sulfur trioxide and compounds capable of liberating sulfur trioxide, such as chlorosulfonic acid, react with an amide, such as dimethylformamide, to form a complex which is stable and provides a useful and convenient source of sulfur trioxide for the sulfation of organic com-. pounds. U.S. Pat. No. 2,807,642 discloses the removal of excess sulfur trioxide from reaction mixtures formed during the sulfonation of alkylbenzene detergent intermediates and other reactive organic compounds by means of formation and separation of complexes with a wide range of carboxamides and sulfonamides. Complexes of sulfur trioxide and dialkylacylamides have i been used very little in the sulfonation of benzenoid compounds. Ratcliffe (Cornell University dissertation, 1954) reports that the complex of sulfur trioxide with dimethylformamide sulfonates toluene very slowly but it does not sulfonate benzene at room temperature.

SUMMARY OF THE INVENTION trioxide, and a dialkylacylamide, such as N,N-dimethylformamide. to produce a 4(or 6-)-monosulfonated derivative thereof. In a preferred aspect, this invention resides in a process for sulfonating a dicarboxamide of metaphenylenediamine. which dicarboxamide can be polymeric. by contacting it with at least one molecular proportion of sulfur trioxide and of dimethylformamide or dimethylacetamide for each gram formula weight of meta-phenylenediamine moieties in the dicarboxamide at 25-90C. for 15 minutes to 72 hours.

DETAILED DESCRIPTION OF THE INVENTION The material to be sulfonated, sulfonating agent, and dialkylacylamide can be contacted in the processes of this invention in any convenient way. For instance, the material to be sulfonated can be added to a solution of the sulfonating agent in an excess of the dialkylacylamide. Alternatively, the sulfonating agent can be added to a solution of the material to be sulfonated in the dialkylacylamide. Generally, it is better to avoid adding the dialkylacylamide to a mixture of the material to be sulfonated and the sulfonating agent in order to avoid any premature reaction, such as degradation of the material to be sulfonated. Sulfonation is carried out by maintaining the material to be sulfonated, the sulfonating agent and the dialkylacylamide in mutual contact for a combination of temperature and time which effects significant sulfonation, which combination can easily be determined by routine experimentation from a consideration of the reactivities of the material to be sulfonated and the sulfonating agent. For example, poly( meta-phenylenediamine isophthalamide a useful starting material in the process of this invention, is sulfonated smoothly and without any appreciable evolution of heat by sulfur trioxide in dimethylformamide in 24 to 48 hours at about 25C.; sulfonation is essentially complete after a few hours at a temperature of 4080C. and in less than one hour at temperatures above about C. Temperatures as high as l40C. may be required for substantial sulfonation in a few hours with less reactive sulfonating agents. such as chlorosulfonic acid and sulfuric acid. The reaction can be carried out at atmospheric pressure at temperatures up to the atmospheric pressure boiling point of the dialkylacylamide. A temperature of 25-90C. is preferred since such temperatures are more conveniently obtained and controlled in inexpensive chemi cal process equipment. Contact times between about 15minutes and about 3 days are preferred.

The proportions of reactants present in the sulfonation reaction mixtures described herein are not critical. Sulfonation is conveniently obtained with mixtures containing 5-20 weight percent of the material to be sulfonated, the maximum concentration with polymeric materials being limited by the inconvenience of handling viscous solutions. Significant sulfonation can be obtained with mixtures containing as little as 1 weight percent of the sulfonating agent. Preferably, the mixture contains at least one molecular proportion of sulfonating agent for each gram formula weight of meta-phenylenediamine in the material being sulfonated. The reaction mixture preferably contains at least one molecular proportion of dialkylacylamide for each molecular portion of sulfonating agent. There is little advantage in using quantities of the sulfonating agent significantly greater than stoichiometric since sulfonation continues only until one sulfonic acid group is introduced into each reactive meta-phenylenediamine moiety. Additional dialkylacylamide can be present in the reaction mixture as a solvent and diluent for the other ingredients of the mixture.

The sulfonation reaction can be followed by techniques well known in the art. For example, the sulfonated product can be isolated and shown to contain sulfur by chemical analysis or by studies of infrared specsuch solutionswith water.

v progressof the sulfonation reaction can be followed by diluting small'aliquots of the reactionmixture with water. Increased sulfonation is indicated by the precipitation of smaller amounts of the starting material until chlorosulfonic acid and its methyl ester, methylsulfu'ric I acid, dimethylsulfate, diethyl sulfate, sulfamic acid,

the product becomescompletely water soluble. With polymeric materials which are useful as permselective membranes, jsulfonation is indicated by the greater water permeability of membranes made from sulfonated polymers as compared to similar membranes made from unsulfonated polymers. With polymers such sulfuric acid and mixtures of'sulfu'ricacid aiid'dehydrating agents, such'as acetic anhydride. l

The dialkylacylamide employed in the process of the invention can be represented by the formula -w er i R s or az,

as the poly(meta-phenylenediamine phthalamides),

and their lithium and calcium salts, having inherent viscosities of about 1 2, the progress of the sulfonation reaction can be followedbypouring a portion of the sulfonation' reaction mixture (optionally neutralized with lithium, or calcium hydroxide) into rapidly stirred acetone, separating the precipitated polymer, by filtration, rinsing withwater on the filter to remove acidic materials, drying, redissolving the polymer in dimethylacetamidqand diluting the polymer solution with water. Unsulfonated polymers are precipitated in the acetone and are recovered essentially unchanged in proper-ties upon dilution of their dimethylacetamide solutions with water. Significantly sulfonated polymers (containing more than about 1 percent sulfur) swell upon rinsing with water after their precipitation with acetone,"with a'decr'ease in the rate of water passage through the polymer during such rinsing. Such polyme'rs'containing about 2.54 percentisulfur formviscous colloidal"dispersionsupon' dilution .of their dime'thy' lacetan'iide solutions with water. Sulfona ted polymers'containing more than about 4 percent sulfur form clear,- visco'us, gelatinous masses upon dilution of The-sulfona'ted product can be isolatedfrom the reaction mixture byco'nv entional procedures which can be modified by those skilled inth'e art. Certain reaction products can be precipitated by pouring the reaction mixture into a liquid in which the'pr oduct is insoluble; Since many of the sulfonated products are more soluble in the acid form,, it is. usually preferable to neutralize the sulfonat'ion mixture with a base,such as calcium or lithiurn hydroxide, and then to precipitate the salt, for example, in acetone or another similar liquid in which the salt is insoluble. The precipitated salt can be washed free of other materials with alcohol or a solvent for the other materials. Such salts frequently show higher inherent viscosities (measured at low concentrations in 'dimethylacetamide) than the unsulfonated polymers. v

A wide variety of sulfonating agents are operable in theprocess of the present invention. Sulfur trioxide is the preferredsulfonating agent because of its low cost and ready availability and because of the lowertemperalkyl, R and R conjointly is C alkylene oroxalkylene or azalkylene'containing 3-4 carbon atoms and one-oxygen or nitrogen atom, and R and'either R" or R conjointly is 0 alkylene which with the 0=(I3 I|q moiety. Preferably, the totalnumber of carbonatoms in R, R and R is no greater than seven because of the more convenient and 'les sjexpensive preparation of such dialkylacylamides. The preferred materials, because of their commercial availability, are N,Ndimethylformamide and N,N-dimethylacetanride. but e ueful. ,a'r'ew uaaterialsi .flN-tt sthyl-N- butylformamide N-methyl N-ethylpropionamide and N,N-diethylacetamide; When-R and R conjointly is C alkylene, it forms with the nitrogen atom of the formula apyrrolidine or piperidine moietyQN- Acetylpiperidine exemplifies such a dialkyl'acyla mide whenR is CH .-When-R?=and R conjointly is 3-oxa l ,S-pentylene or 3'-az'a-,I ,S-pentylene, it forms with the nitrogen atom of the formula a morpholin e or piperazine moiety. N-Formylmo'rpholine and N-formylpiperazine exemplify such dialkyla'cylamideswhen R is H.

1 mamide complex forms readily upon-addition of liquid or gaseous sulfur trioxide to an excess of dimethylformamide with cooling-to O10C. It is soluble in dimethylformamide, to the extent of about 15 weight percent and, at such concentration, is conveniently stored and/ @2899 The w nls ll were linq h f times with the evolution of large amounts of heat. For

atures' at which it is reactive. It can be used in the form of oleum (that is, fuming sulfuric acid or solutions of tion mixtures containing organic amides in which the examplein order to controlthe reaction when dimethylacetamide is employed, liquid sulfur trioxide .is added to an equal weight of a mixture of dimethyla cetamide' and chloroform at 0-10C. or,.alternatively if higher 1 temperatures are used, a solution of sulfur trioxide in hydrogen atoms attached to the amide nitrogen have been replaced by hydrocarbon radicals or substituted hydrocarbon radicals, for example, as disclosed in U.S. Pat. No. 2,506,580. Useful-sulfonating agents include compounds of the general formula ROSOQX in which R is hydrogen or C, alkyl' and X is-hy droxy,amino,

chloroform is added to an excess -of dimethylacetamide, orgaseous Isulfur trioxide is bubbled slowly into 'dimethylacetarnide. It is to be understood,'however, thatthe present invention does "not requirev the formation of such complexes in the reaction mixture.

sulfonated inthe process of the in Materials which can be sulfonated by the process of this invention are diamides, that is, diacylamides, of meta-phenylenediamine. The diamide can be a dicarboxamide, a disulfonamide or a mixed carboxamidesulfonamide and, as such, contains the NHCO and/or NH-SO moiety. The dicarboxamides are preferred herein. In order for monosulfonation to occur, at least one of the two phenylene ring positions which are ortho to one amino group and para to the other must be free of a substituent. Even though both such positions are free of substitucnts, only one becomes sulfonated during the reaction. Considering meta-phenylenediamine as 1,3-diaminobenzene, at least one of the 4- and 6- positions must be unsubstituted. The 2-, 5- and remaining 4- or 6- position can be substituted with an inert substituent, that is, one which does not enter into, affect or prevent sulfonation of the ring at the 4- or 6- position. For example, the substituents which are inert include alkyl, preferably C alkyl. and halo, preferably chloro. The preferred diamides of meta-phenylenediamine are unsubstituted.

It has been discovered that the starting material must be a diamide of meta-phenylenediamine for sulfonation to occur according to the process of this invention. For example, although the bis-benzamide of metaphenylenediamine is sulfonated by this process, the hisbenzamide of para-phenylenediamine is not, nor is the mono-benzamide of aniline (benzanilide).

As derivatives of carboxylic acids the preferred useful diamides are derivatives of monoor dicarboxylic acids containing 1-18 or 2-18 carbon atoms, respectively, or benzenoid carboxylic acids containing 7-10 carbon atoms. The preferred derivatives of monocarboxylic acids are monocarboxylic acids containing 1-4 carbon atoms. Included are derivatives of acetic, oxalic, benzoic and the phthalic acids. As derivatives of sulfonic acids, the diamides preferably are derivatives of benzenoid sulfonic acids containing 6-9 carbon atoms, for example, benzeneor toluenesulfonic acid.

The useful diamides of meta-phenylenediamine can be derivatives of carbonic acid and thus are known as,

ca'rbamates or urethanes and contain the NHCO moiety. Similarly, the diamides can contain the urea moiety 'NHCONH or the semicarbazide moiety 'NHCONI-INH-. Such urethanes, ureas and semicarbazides can be derivatives of C alkyl or C aryl alcohols, amines or hydrazines.

, forming and fiber-forming but low enough to be soluble in practical solvents so that films and fibers can be formed from their solutions. Such polymers have inherent viscosities above about 0.6 (measured at a concen- Aromatic polyamides which can be sulfonated by the process of this invention are well known. They can be prepared, for example, by the low temperature solution condensation of one or more aromatic diamines with one or more dibasic acid chlorides. Such processes are described in US. Pat. Nos. 3,094,511; 3,232,910; and 3,240,760, and British Patent 1,104,41 1 and by Morgan in Polymer Reviews, Volume 10, Condensation Polymers, lnterscience Publishers, New York (1965). They also can be prepared by reaction of one or more aromatic aminoacid chlorides with one or more meta-phenylenediamines, followed by reaction of the resulting intermediate diamide with one or more dibasic acid chlorides.

Aromatic (polyamide-hydrazides) containing metaphenylenediamine moieties which can be sulfonated as described herein can be prepared by the condensation of one or more aromatic aminocarboxylic hydrazides with one or more dibasic acid chlorides. Such processes include that described by Culbertson and Murphy in Polymer Letters-Volume 5, pages 807-812 (1967). Aromatic poly(diamide-dihydrazides) can be prepared by reaction of one or more nitroaromatic acid chlorides with one or more dicarboxylic dihydrazides, reducing the resulting aromatic dinitrodihydrazide to an aromatic diaminodihydrazide, and condensing the aromatic diaminodihydrazide with one or more dibasic acid chlorides to give the aromatic poly(diamidedihydrazide). Such processes include that described by Frost et al. in the Journal of Polymer Science, Volume A-l, pages 215-233 (1968).

Aromatic polysemicarbazides can be prepared by the reaction of one or more dicarboxylic dihydrazides with one or more aromatic diisocyanates. Such processes include that described in' US. Pat. No. 3,004,945 and by Campbell et al. in the Journal of Applied Polymer Science, Volume 2, pages 155-162 (1959). Aromatic polyur'eas can be prepared by the reaction of one or tration of 0.5 weight percent) and are soluble to the exmore diamines with one or more aromatic diisocyanates. Such processes include that described in US. Pat. No. 2,888,438.

In carrying out the process of this invention the reaction mixture can contain materials other than the diamide, sulfonating agent and dialkylacylamide, provided that the material is inert under the reaction conditions. Such materials can be organic or inorganic. For example, they can be diluents or solvents such as aromatic and chlorinated hydrocarbons or they can be inorganic salts. Such diluents and salts can be already present in the diamide starting material or they can be added as desirable ingredients to the sulfonation reaction mixture. Salts which can be added and which are useful for increasing the solubilities of aromatic polyamides in dimethylformamide, dimethylacetamide and N-methyl-2- pyrrolidone, and especially aromatic polyamides which are used in the preparation of permselective membranes, include calcium chloride, calcium bromide, magnesium chloride, strontium chloride, lithium chloride, lithium bromide, lithium nitrate, sodium bromide and ammonium bromide. The advantages of such salts are disclosed in US. Pats. Nos. 3,068,188 and 3,567,632. I

Useful diluents include solvents such as disclosed in US. Pat. No. 3,063,966 for the condensation of aromatic diamines with aromaticdiacid dihalides, which solvents have an average solute-solvent interaction energy with complementary model compounds represenpolyamides containingthe meta-phenylenediamine moiety to obtain randomly substituted polymers with high inherent viscosities and high degrees of sulfona-. tion' without significant polymer degradation. The process is particularly practical'in that it can be carried out on polyamides without isolation of the polyamides from the solutions in which they are obtainedby condensation reactions. I v Y i r The sulfonation process of this-invention makes possible the production of formed and shaped structures of sulfonated aromatic polyamides from metaphenylenediamine and phthaloylchlorides without intermediate isolation of the sulfonic acid-containing polymer. For example, meta-phenylenediamine optionally containing other diamines can be condensed with one or more phthaloyl chlorides in solution in a dialkylacylamide to obtain a solution of a poly(metaphenylenediamine phthalamide) containing hydrogen chloride, and then sulfur trioxide 'or a material forming sulfur trioxide can be added, to the polymer solution.

The mixture is heated, if n ecessary'or desirable, to obtain sulfonation or to increase the rate .of sulfonation, and a base such as calcium or lithium hydroxide is added to neutralize the acidic materials in the mixture (the inorganic salts which precipitate can be separated). A shaped structure can be formed from' the re- Example 1 Liquid sulfur trioxide (cornmercially available under v the name -SuIfan") was added dropwise'with stirring and cooling to drydimethylformamide atsuch a rate 5 that the temperature did not exceed 10C. The resulting solution containing about 6 weight percent sulfur trioxide was diluted with dimethylformamide to a sulfur trioxide content of about 3 percent. Into a glass jar wereplaced 5- grams of the bis-benzamide of metaphenylenediamine (melting point 240243C., ob.- tained by reaction of meta-phenylenediamine and benzoyl chloride) and 45 grams of the 3 percent solution of sulfur trioxide in dimethylformamide. 1'l"he jarwas tumbled slowly at ambient temperature for three days. The reactionmixture was completely miscible with water, indicating substantially complete sulfonation.

. 8 Water dilution of asimilar mixture immediately after mixing resulted in precipitationof the bis-benzamide.

Example 2 v A mixture of 5 grams of the bis( benzenesulfonamide of v meta-phenylenediamine (melting point 192- l95C.) and 45 grams of a 5 percent solution of sulfur trioxide in dimethylfo rmamide was maintained at 78C. for 6 hours. The reaction product was completely so'luble'when the mixture was diluted with waterQindicating substantially complete sulfonation. The starting material was recovered substantially unchanged by water dilution of a similar mixture kept at ambient temperature for three days. v I

I Example 3 7 In 493 grams of a 10.7 percent solution of sulfur trioxide in dimethylformamide were dissolved 40 grams of a polymer'obtained by the condensation of metaphenylenediamine with a /30 mixture of isophthaloyl chloride and terephthaloyl chloride. The resulting solution was placed in a glass jar and the jar was slowly tumbled at ambient temperature for three days. To this mixture was added a slurry of 25.6 grams of lithium hydroxide in 25 ml. of water. The resulting mixture was poured into rapidly stirred acetone. The precipitated polymer was rinsed several times with acetone and then with 95 percent ethyl alcohol. After drying. the resulting polymer containedlOJ percent total sulfur and less than Ol2 percen't inorganic sulfur, indicating the presence of approximately one sulfonicacid group for each two aromatic'rings in the polymer chainfA portion of the sulfonated polymer was refluxed in 10 percent aqueous sodium hydroxide for'three hours to hydrolyze the polyamide and obtain a mixture of water soluble sodium salts. The resulting solution was cooled and acidified with aqueous hydrochloric acid to precipitate a mixture of isophthalic and terephthalic acids. The precipitated mixture of acids was separated by filtration. Thefiltrate was neutralized with sodium carbonate and evaporated to dryness. The residual sodiumjsalts were extracted witha solution of calcium chloridein dimeth:

ylacetamide to convert sulfonic acids present to soluble calcium salts., Theresulting solution was diluted with benzene and the oil which'formed was separated. This oil was dissolved in water andconverted into a dihydrochloride salt by adding concentrated aqueous hydrochloric acid. The infrared spectrum of the isolated dihydrochloride salt was essentially identical in all significant details to that of an authentic sample of the dihydrochloride salt of 2,4-diaminobenzenesulfonic acid and contained no evidence of significant amounts of a sulfophthalic acid, thereby demonstrating that the sulfo-z nated polymer was essentially a polyphthalamide of 2,4-diaminobenzenesulfonic acid. 7

Example 4 [n grams of a 3 percent solution of sulfur trioxide in dimethylformamide were dissolved approximately 15 grams of the condensation polymer employed in the sulfonation step of Example 3. The resulting solution was place in a glass jar and the jar was slowly tumbled atambient temperature for three days. To the mixture was added 1.8 grams of lithium hydroxide, sufficient to neutralize unreacted sulfur trioxide and to convert the sulfonated product to its lithium salt. The mixture was slowly tumbled for an additional two hours and then poured into rapidly stirred acetone. The precipitated polymer was rinsed several times with acetone and then with 95 percent ethyl alcohol. After drying, the polymer contained 4.8 percent total sulfur, an amount corresponding approximately to one sulfonic acid group for each four aromatic rings in the polymer chain.

A prior art procedure, for example, as disclosed in US. Pat. No. 3,567,632, was used to prepare asymmetric permselective membranes with both the unsulfonated polyamide and the sulfonated polyamide. After a two-week exposure in reverse osmosis test cells to 0.5 percent aqueous sodium chloride at 600 psi. under conditions such that approximately 10 percent of the solution fed to the test cell passed through the membrane, the membrane made with the unsulfonated polymer had a water permeability of 6.3 gallons per sq. ft. per day and a salt passage of 3.1 percent and the membrane made with the sulfonated polymer had a water permeability of 35.1 gallons per sq. ft. per day and a salt passage of 15.5 percent.

Example 5 Into a glass jar were introduced 7.5 grams of the condensation polymer employed in the sulfonation step of Example 3 and 40.2 grams of a 6.2 percent solution of sulfur trioxide in dimethylformamide. The jar was slowly tumbled for three days at ambient temperature. To the reaction mixture were added 1.1 grams of lithium hydroxide and the jar was tumbled for an additional one day. To the neutralized solution were added 2.25 grams of lithium nitrate and the resulting mixture was filtered to remove insoluble material (mostly lithium sulfate). Without isolation of the polymer, a prior art procedure, for example, as disclosed in US. Pat. No. 3,567,632, was used to prepare an asymmetric membrane which had a water permeability of 19.9 gallons per sq. ft. per day and a salt passage of 25 percent under the test conditions described in Example 4.

Example 6 To 50 grams of a 7.5 percent solution of sulfur trioxide in dimethylformamide were added 5 grams of the condensation polymer employed in the sulfonation step of Example 3. The mixture was heated with stirring to 80C. and held at this temperature for minutes. The mixture was then cooled to ambient temperature and poured into rapidly stirred acetone. The precipitated polymer was separated by suction filtration, rinsed extensively with acetone, and dried. A portion of the dried polymer was dissolved in a relatively small volume of dimethylacetamide and the solution was diluted with water, forming a clear gelatinous mass characteristic of similar mixtures containing highly sulfonated poly(meta-phenylenediamine phthalamides).

Example 7 Example 8 Into a jar were introduced 10 grams of the condensation polymer employed in the sulfonation step of Example 3 and a solution of 12 grams of chlorosulfonic acid in 108 grams of dry dimethylformamide. The jar was slowly tumbled at ambient temperature for 3 days. The reaction mixture was then poured into rapidly stirred acetone and the precipitated polymer was washed thoroughly and dried. The sulfonated polymer contained 1.5 percent total sulfur.

Example Example 8 was repeated except that dimethylacetamide was used in place of dimethylformamide. The sulfonated polymer contained 2.1 percent total sulfur.

Example 10 Example 9 was repeated except that the reaction was carried out in a small round flask fitted with a drying tube and the flask was placed in a bath maintained at 45C. Agitation was effected by stirring rather than by tumbling. The sulfonated polymer contained 6.8 percent total sulfur.

Example 1 1 To a solution of 7 grams of dimethyl sulfate in 50 grams of dimethylformamide were added 5 grams of the condensation polymer employed in the sulfonation step of Example 3. The resulting solution was heated with stirring at l20130C. for two hours and then cooled to ambient temperature. The mixture was poured into rapidly stirred water; The precipitated polymer was collected by filtration, rinsed several times with water, and dried at C. A clear gelatinous mass, characteristic of extensively sulfonated poly(- meta-phenylenediamine phthalamides), was obtained upon dissolving a portion of the product in dimethylacetamide and diluting same with water. No detectable sulfonation was obtained in three days at ambient temperature with a similar reaction mixture.

Example 12 To a cooled mixture of 750 parts of chloroform and 750 parts of dimethylacetamide were added 250 parts of liquid sulfur trioxide. The mixture was diluted with about 3,500 parts of dimethylacetamide to obtain a so lution containing approximately 5 percent sulfur trioxide. Into a glass jar were introduced 15 grams of the condensation polymer employed in the sulfonation step of Example 3 and grams of the 5 percent sulfur trioxide solution. The jar was slowly tumbled at ambient temperature for 3 days. To the reaction mixture were then added 5.5 grams of lithium hydroxide and the sulfonated polymer was isolated as described in Example 3. The dried polymer contained 9.1 percent total sul- 'fur.

Example 13 aqueous systems. The isolated polymer was dried at 100C. A portion of the dried polymer was dissolved in dimethylacetamide to produce a 15 percent solution The resulting solution wascoated onto a glass plate and the plate was heated by means of a hot plate for a few minutes at 100C. and then immersed in water. The

film so obtained had properties, including tensile properties, characteristic of films of sulfonated poly(metaphenylenediamine phthalamides) which are prepared by the procedure of Example 1. When the experiment was repeated except that heating was carried out at l20l 30C., the starting polymer was recovered without significant change by pouring the cooled mixture into rapidly stirred ice cold water and rinsing to remove acidic materials. When the experiment was carried out at 140C. without the dimethylformamide, signifcant polymer degradation occurred; upon reducing the reaction temperature to 120C., the starting polymer was recovered without significant change.

Example 14 To 60 grams of ice cold dimethylformamide were added, in small portions and with stirring, 7 grams of fuming sulfuric acid containing about 20 percent free sulfur trioxide. To the resulting solution were added 5 grams of the condensation polymer employed in the sulfonation step of Example 3. The mixture then was tumbled slowly at ambient temperature for two days in a tightly closed Jan The reaction mixture was poured into stirred ice cold water and the precipitated polymer was collected by suction filtration, rinsed with water to remove residual acid, and dried. Upon dissolving a smallamount of the polymer in dimethylacetamide and diluting same with water, a clear gelatinous mass, characteristic of highly sulfonated polyamides, was produced. A film prepared as described in Example 13 indicated that the polymer had undergone no significant reduction in tensile properties.

Example 15 polymer in a small volume of dimethylacetamide and diluting same with water, a clear gelatinous mass, indicative of extensive sulfonation, was obtained. A film of this sulfonated polymer prepared as described in Example 13 showed that the polymer had undergone no significant loss in tensile properties.

Example 16 The experiment described in Example 15 was repeated employing dimethylacetamide in place of dimethylformamide. After stirring the reaction mixture for 16 hours at ambient temperature, a small amount of the mixture was treated to recover polymer. When the isolated polymer was dissolved in dimethylacetamide and diluted with water, it precipitated, an indication that it was unsulfonated. The remaining portion of the reaction mixture was then heated with stirring at C. for 45 minutes and the polymer was isolated therefrom. Upon dissolving a portion of the polymer in dimethylacetamide and subsequently diluting same with water, a clear gelatinous mass, characteristic of highly sulfonated poly(meta-phenylenediamine phthalamides), was produced. A film prepared as described in Example 13 indicated that the polymer had undergone no apparent degradation or reduction in tensile properties.

Example 1 7 To a solution of 10 grams of sulfamic acid in grams of dry dimethylformamide were added 10 grams of the condensation polymer employed in the sulfonation step of Example 3 and the mixture was tumbled for 3 days at ambient temperature in a tightly sealed jar. Preliminary tests. including precipitation of a portion of the reaction mixture by pouring into water and dissolution of the polymer in mixtures of dimethylacetamide and water, indicated that no significant sulfonation had occurred. The reaction mixture was then heated to 70-80C. for 4 hours. The polymer was isolated by precipitation in water, filtration, and rinsing with acetone. During the rinsing there was a reduction in the rate of filtration, characteristic of the polymer swelling obtained with sulfonated poly( meta-phenylenediamine phthalamides). A small amount of the dry polymer was dissolved in dimethylacetamide. Addition of water to the resulting solution produced a viscous transparent gelatinous mass, indicative of extensive sulfonation.

Example 1 8 A polymer with an inherent viscosity of 0.53 (measured at ,a concentration of 0.5 weight percent in dimethylacetamide) was prepared by condensing 2,4-diaminoisopropylbenzene and a 70/30 mixture of isophthaloyl chloride and terephthaloyl chloride. To l6 grams of this polymer were added 200 ml. of dimethylformamide containing 10 percent sulfur trioxide. The mixture was heated with stirring at C. for 1.5 hours and then cooled to 25C. Anhydrous lithium hydroxide (12 grams) was added to neutralize acidic materials and the mixture was poured into rapidly stirred satu rated aqueous sodium chloride. The precipitated polymer was collected by suction filtration and washed with water until the washings were neutral and free of chloride. The rate of filtration under suction became progressively slower due to polymer swelling. The isolated lithium salt of the sulfonated polymer wassoluble in a 50/50 (volume) mixture of acetone and water and had an inherent viscosity of 3.0 (measured at a concentration of 0.5 weight percent in dimethylaeetamide).

Example 19 Employing a prior art procedure, for example, such disclosed by Bornwater in Recuiel dc Traveaux Chemiquc, Volume 12, pages 105-141 (1912), oxalyl chlo ride was added in a stoichiometric amount to a mixture of equal amounts of orthonitroaniline and metanitroaniline in tetrahydrofuran containing trimethylamine. The resultant precipitate containing trimethylamine hydrochloride and a high melting mixture of 2,2- dinitrooxanilide and 3,3'-dinitrooxanilide was separated by filtration. The filtrate was diluted with water to precipitate 2,3-dinitrooxanilide, melting point 240245C. The 2.3-dinitro compound was reduced with hydrogen using a palladium-on-charcoal catalyst to obtain 2.3-diaminooxanilide, melting point 180183C. A polyamide was prepared by condensation of the diamino compound with a 70/30 mixture of isophthaloyl chloride and terephthaloyl chloride. A mixture of grams of the polyamide and 150 grams of a 5 percent solution of sulfur trioxide in dimethylformamide was slowly tumbled in a glass jar at ambient temperature for 3 days. To the reaction mixture were added 3.5 grams of lithium hydroxide and the polymer was isolated as described in Example 3. An asymmetric membrane. prepared and tested as described in Example 4. had a water permeability of 382 gallons per sq. ft. per day and a salt passage of 26 percent. A similar membrane made from the unsulfonated polymer had a water permeability of 4.5 gallons per sq. ft. per day and a salt passage of 9.1 percent under the same test conditrons.

Example the unsulfonated polymer and from a mixture of one part of the sulfonated polymer and three parts of the unsulfonated polymer. The membrane made from the unsulfonated polymer had a water permeability of 2.6

gallons per sq. ft. per day and a salt passage of 22 percent. The membrane made from the mixture of sulfonated and unsulfonated polymers had a water permeability of 21.7 gallons per sq. ft. per day and a salt passage of 8 percent under the same test conditions. I

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Process for sulfonating a polymeric dicarboxamide of a dicarboxylicacid of 2-18 carbon atoms and a metaphenylenediamine which is unsubstituted in at least one of the two phenylene ring positions which are ortho to one amino group and para to the other. which process comprises contacting the polymeric dicarboxamide, an effective amount of a sulfonating agent selected from sulfur trioxide and agents having the formula ROSO X wherein R is H or C alkyl and X is hydroxy, amino, C alkoxy or chloro and an N,N- dialkylacylamide at a temperature and for a time until the desired sulfonation is completed.

2. The process of claim 1 wherein the dialkylacylamide has the formula wherein R is H or C, alkyl. R and R each'is C alkyl, R and R conjointly is C,. alkylene. C monooxalkylene or C monoazalkylene. and R and either of R and R conjointly is C,, alkylene.

3. The process of claim'l wherein the sulfonating agent is sulfur trioxide and the dialkylacylamide is N,N-dimethylformamide.

4. The process of claim 1 wherein the sulfonating agent is chlorosulfonic acid and the dialkylacylamide is N,N-dimethylformamide.

5. The process of claim 1 wherein the sulfonating agent is sulfuric acid and the dialkylacylamide is N,N-dimethylformamide.

6. The process of claim 1 wherein the sulfonating agent is sulfur trioxide and the dialkylacylamide is N,N- dimethylacetamide. V

7. The'process of claim 3 which is carried out at 2590C. for 15 minutes to 3 days with a film-forming poly(meta-phenylene phthalamide) as the polymer.

8. The process of claim 7 wherein there is present one molecular proportion of sulfur trioxide and one molecular proportion of dimethylformamide for each gram formula weight of meta-phenylenediamine moiety in the polymer. 

1. PROCESS FOR SULFONATING A POLYMERIC DICARBOXAMIDE OF A DICARBOXYLIC ACID OF 2-18 CARBON ATOMS AND A METAPHENYLENEDIAMINE WHICH IS UNSUBSTITUTED IN AT LEAST ONE OF THE TWO PHENYLENE RING POSITIONS WHICH ARE ORTHO TO ONE AMINO GROUP AND PARA TO THE OTHER, WHICH PROCESS COMPRISES CONTACTING THE POLYMERIC DICARBOXAMIDE AN EFFECTIVE AMOUNT OF A SULFONATING AGENT SELECTED FROM SULFUR TRIOXIDE AND AGENTS HAVING THE FORMULA ROSO2X WHEREIN R IS H OR C1-4 ALKYL AND X IS HYDROXY, AMINO, C1-4 ALKOXY OR CHLORO AND AN N,NDIALKYLACYLAMIDE AT A TEMPERATURE AND FOR A TIME UNTIL THE DESIRED SULFONATION IS COMPLETED.
 2. The process of claim 1 wherein the dialkylacylamide has the formula
 3. The process of claim 1 wherein the sulfonating agent is sulfur trioxide and the dialkylacylamide is N,N-dimethylformamide.
 4. The process of claim 1 wherein the sulfonating agent is chlorosulfonic acid and the dialkylacylamide is N,N-dimethylformamide.
 5. The process of claim 1 wherein the sulfonating agent is sulfuric acid and the dialkylacylamide is N,N-dimethylformamide.
 6. The process of claim 1 wherein the sulfonating agent is sulfur trioxide and the dialkylacylamide is N,N-dimethylacetamide.
 7. The process of claim 3 which is carried out at 25*-90*C. for 15 minutes to 3 days with a film-forming poly(meta-phenylene phthalamide) as the polymer.
 8. The process of claim 7 wherein there is present one molecular proportion of sulfur trioxide and one molecular proportion of dimethylformamide for each gram formula weight of meta-phenylenediamine moiety in the polymer. 